High-Performance Natural Melanin/Poly(vinyl Alcohol-co-ethylene) Nanofibers/PA6 Fiber for Twisted and Coiled Fiber-Based Actuator

Twisted and coiled fiber-based actuators have drawn a great attention because their unique structure can provide mechanical response with the external thermal stimulus. Herein, an ultra-fast and light-weight twisted and coiled fiber-based actuator was designed based on a nature melanin/poly (vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers/PA6 composite fiber. In brief, PA6 was firstly coated by melanin/PVA-co-PE nanofibers using a spraying method, followed by the twisting and coating the composite fiber to obtain the actuator. The excellent photothermal property of melanin contributed to the superior performance of the actuator, whereas the PVA-co-PE nanofibers was responsible for the uniform distribution of melanin and the enhanced mechanical property of the prepared-actuator. This unique design has led to the high performance of the melanin/NFs/PA6 fiber-based actuator, whose torsion actuation can reach to 14,000 rpm, and maximum tensile actuation was − 6.36% at temperature difference of 40 ℃. In addition, the tensile stress of PA6/NFs/melanin fiber was about four times higher than PA6 filaments. Owing to the simple and environmental-benign preparation method, as well as the excellent efficiency of twisted and coiled melanin/NFs/PA6 fiber-based actuator, this study highlights the facile design of the composite fiber for high-performance fiber-based actuators. This fiber-based actuator is promising for application in energy generator.